Method of making sound reproducers



:Jan. 2, 1934. v P. 1.. JENSEN 7 1,941,476

METHOD OF MAKING SOUND REPRODUCERS Filed June "27, 1930 ZSheets-Sheet l III/fill.

Jan. 2, 1934. JENSEN 1,941,476

IETHOD OF MAKING SOUND REPRODUCERS Filed June 27, 1930 2 Sheets-Sheet 2 m 47mm Patented Jan. 2, 1934 PATENT OFFICE- METHOD OF MAKING somm nnrnonuonns Peter L, Jensen, La Grange, Ill., aalignor to Jensen Radio Manufacturing Company, Ohicago, 111., a corporation of Nevada Application June 27, 1930. Serial No. 464,275

3 Claims. (01. 29-1555) My invention relates to sound reproducers, particularly of the electro-dynamic or moving coil type, in which the coil is disposed, so as to be freely movable, in an annular field between the inner and outer pole pieces, and contemplates an improved method of and means for concentrically disposing the pole pieces with respect to each other.

The invention is illustrated in the accompanying drawings in which:

Figure 1 is a fragmentary section taken longitudinally along the axis of a device embodying the invention; a

Figures 2 and 3 are more or less diagrammatic sectional views partially in elevation, and showing the steps of forming the positioning means on the case and end plate parts, respectively;

Figure 4 is a more or less diagrammatic view similar to Figure 2, and showing an alternative manner of forming the positioning means on the case part; 7 1

Figure 5 is a more or less diagrammatic view similar to Figure 3, showing an alternative manner of forming the positioning means on the end plate part;

Figure 6 is an end view on a reduced scale of the device shown in Figure'l;

Figure 7 is a longitudinal axial section thru the case and end plate parts showing a modified form of positioning means on the parts; and

Figures 8 and 9 are more or less diagrammatic views showing the steps of forming the positioning means shown in Figure 7.

Referring to the drawings, the device shown in Figure 1 comprises a case 5, inner pole piece or core 6, and an end plate constituting the circumferential or outer pole piece.

A frame 8 has a radial portion 9 secured. to the end plate 7 by rivets 10, and from the radial portion 9 the frame 8 extends generallyconically and is of open work' formation at 11. For increasing the m etic area or depth in the l outer pole piece '7 a supplemental outer pole piece ring 12 is secured to the pole piece 7 by the rivets 10, the radial portion 9 of the frame 8 being ofiset at 13 to accommodate it to the in-' terposed ring 12.

The generally conical diaphragm 14 is yieldingly attached around its outer periphery at 15 to the frame 8, and its inner truncated end is rigidly secured at 16 to an insulating coil carrying sleeve 1'7. The movable coil 18 is wound upon and preferably firmly cemented to the outer surface of the sleeve 1'1.

The inner pole or core piece 6 is riveted or rigidly secured at 19 to the end 20 of the case 5, which end 20 may be provided with a ring piece 21 for increasing the magnetic area. A magnetizing coil 22 may be placed around the core 6, being insulated therefrom by an annular layer lating rings 25 and 26 are disposed at the opposite ends, of the coil 22, a brass spacing ring 2'7 offset marginally at 28 being loosely interposed between the ring 25 and the pole piece 7.

'Ihe inner truncated end 16 of the diaphragm 14 is anchored for free movement with the coil 22 by non-radial spring arms 30, secured at their outer ends to lugs 31, struck up from the frame 8, and at their inner ends to a ring element 32 surrounding the sleeve 17, and between which and the sleeve 17 the adjacent end of the diaphragm 14 may be secured.

The case 5 is flanged radially at 35 and may be secured to the pole piece 7 and frame 8 by screws 36 passing loosely through registering openings 37 and having threaded engagement in nuts 38.

Now; in order to dispose pole pieces 6 and 7 concentrically with respect to each other, I provide the flange 35 of one pole piece part, namely, the casing 5 with positioning means 40 and the other pole piece part, namely, the pole piece 7 itself is provided with positioning means 41 which engages with the positioning means 40 and disposes the pole pieces 6 and '1-c0ncentrica11y,thereby forming a uniform annular space between the inner and outer pole-pieces and assuring a uniformity of the field by the simple expedient of assembling the parts.

In the embodiment of Figures 1, 2 and 3 the positioning means 40 is in the form of a plurality of dowel sockets or openings preferably equidistant apart circumferentially around the flange 35, the positioning means 41 comprising cooperating and similarly positioned dowel pins on the pole piece 7. The dowel pins 41 are shown as 105 being pressed or extruded out' of the metal of the pole piece 7, but separate pins may be attached to the pole piece 7 in accordance with this invention.

In Figure 2 is shown the step of forming the no being shown as opening entirely through the flange 35, although it is to be understood that they may be only depressed therein if desired.

The forming elements, therefore, may be in the form of drills 45, one being shown for each socket or opening 40, and these drills are carriedby a carriage 46 having movement toward and from the case support 4'7. The forming elements are spaced according to the desired spacing and arrangement of positioning means 40. A centering element 48 also carried by the carriage 46 has a socket 49, the axis of which is equi-distant from the axes of the drills or socket forming elements 45. The internal diameter of the socket 49 is equal to the external diameter of the pole piece 6, and'the lower end of the socket 49 flares outwardly and projects below or beyond the ends of the forming elements 45 sufiiciently to take over the pole or core piece 6 and center the same with respect to the socket forming elements 45 ahead of the operation of these elements 45 upon the flange 35. A ring 50 on the support positions the case 5 for centering cooperation of the centering element 48 with the core 6.

With the case 5 centered by means of the core 6 with respect to the elements 45 for forming the positioning means 40, this means 40 is formed by the elements 45 upon continued movement of the carriage 46 toward the support 4'7. Upon forming the positioning means 40 the forming elements may be withdrawn and the next case arranged in place and similarly operated upon.

While I have shown and described the forming means 45 as a plurality of elements, it is to be understood that one element might be employed and the carriage arranged to be turned to bring it into position for successively forming the several positioning sockets. This also applies to the means for forming the cooperating positioning means 41 on the outer pole piece '7.

In Figure 3 is shown the step of forming the positioning dowels '41 on the pole piece '7, these dowels 41 being shown as pressed or extruded from the metal of the pole piece '7, but may be in the form of separate pins applied according to this invention to form the dowel means. In the embodiment shown the forming means comprises a die-like block 52 recessed at 53 to receive the pole piece '7 and provided with an axial opening 54 to admit the centering element 55 01' the plunger 56 which is movable toward and from the block 52 and has extrusion elements 5'7 i'or cooperating with extrusion recesses 58 in the block 52 so that upon movement of the plunger 56 toward the block 52 these elements will by their engagement with the pole piece '7, and by their cooperation with the recesses 58 extrude the dowel pin means 41 from the metal of the pole piece '7.

The axes of the extrusion elements 57 are equidistant from the axis of the centering element 55, and the external diameter of the centering element 55 is equal to the internal diameter of the opening 24 in the pole piece '7, and its lower end is tapered at 60 and projects below the elements 57 sufliciently to enter the opening 24 and center the pole piece '7 with respect to the elements 57 ahead of the operation of these elements upon the piece '7. Clearance is shown in the block 52 around the piece '7 to permit this centering, and a slight clearance is shown between the case 5 and ring 50 of Figure 2 to permit the centering of that part oi? the device.

The forming elements 5'7 are not only spaced equi-distantly from the axis of the centering element 55, but the spacing is equal to the spacing of the axes of the forming elements 45 from the axis of the centering element 48 so that when the parts are brought together the entry of the dowel pin element 41 into the dowel socket 40 will accurately dispose the pole pieces in concentric relation without adjustment and by the simple expedient of assembling the parts.

In Figure 4 the means 49' centering the forming elements 45 by means of the inner pole piece 6' is associated with the support 4'7 instead of with the carriage 46, as in Figure 2, it being understood that the elements 45' are centered equi-distantly from the axis of the member 49'.

In Figure 5 the centering element 55 for centering the forming elements 5'7 by means of the pole piece opening 24 is associated with the block 52' instead of with the plunger 56' as in Figure 3, it being understood that the elements 5'7 are centered equi-distantly from the axis of the member 55.

In the embodiment illustrated in Figure 8 the positioning means on the case 50, comprises the radial flange 65, the periphery of which is turned down about the inner pole piece 6a carried by the case 511 as a center, and the cooperating positioning means on the pole piece '7a is formed by turning the marginal edge of the pole piece '7a over marginally at 66 to embrace the periphery of the flange and thereby disposing the pole pieces of these parts concentrically with respect to each other.

In Figure 8 the case 511 is shown more or less diagrammatically as supported at 68 in a suitable chuck, for example, and a tool is shown at 69 for turning the periphery of the flange 65 down about the pole piece 6a as a center. A lathe is contemplated for this purpose.

In Figure 9 is shown the step of turning the marginal edge of the pole piece '7a over at 66. This may be done by die elements or by centering the pole piece '7a by means of the opening 24a and with a suitable tool '70 drawing the marginal edge of the pole piece laterally to turn it over so that it will marginally receive and embrace the periphery of the flange 65 of the case 5a upon assembly of the parts, thereby accurately disposing the pole piece 6a concentrically with respect to the pole piece '7a. It is understood, of course, that the external diameter of the member '70 for turning over the marginal edge of the pole piece 7a is equal to the radius of the flange 65 of the casing, the member 70 being centered with respect to the opening 24a in the pole piece by. engagement of the centering element 72 carried thereby in the pole piece opening 24a, the external diameter of the centering element '72 and the internal diameter of the opening '71 being equal.

In Figure 5 the pole pieces 7' and 12 are shown secured together before the formation of the positioning means. This is also true in Figure 9 but in Figure 3 the positioning means is shown as being formed before joining the pole pieces '7 and 12. This may vary.

I do not intend to be limited to the precise details shown or described.

I claim:

1. The method of mounting and positioning an end plate upon the open end of a cup-shaped casing having a flange at its open end and an inner pole piece secured to and projecting from the base of said casing which comprises engaging over the inner pole piece a socketed member carried by a movable carriage carrying drilling 11 bet in position to engage and form openings in the flange of said casing, moving the socketed member slidingly upon said inner pole piece ahead 01' the movement of said drilling tools to bring said tools into cooperation with the flange of the casing at positions centered with respect to said-inner pole piece, operating said tools to form openings in the flange oi the casing, engaging in the opening in the end plate a pin carried by a plunger carrying centering tools centered with respect tosaid pin to engage and form dowel pins on said plate, moving said pin'through said opening to engage said centering tools with said plate'to form the .dowelpins on the plate, and assembling the end plate upon the open end of the casing with the inner pole piece extending into the opening in said end plate and the dowel pins on said plate in engagement with the openings in the flange oi. the casing.

2. The method of concentrically disposing an inner pole piece secured at one end to and pro jecting from the base of a flanged casing in an opening in a circumferential pole piece constituting an end plate for'said casing which comprises 5 ,centering the casing by means of said inner pole piece, forming positioning means on the centered casing, centering the end plate by means of the.

piece extending into the opening in said end plate and with the positioning means on said end plate in engagement with the positioning means on the casing.

3. The method of concentrically disposing an inner-pole piece secured at one end to and projecting from the base of a flanged casing in an opening in a circumferential pole piece constituting an end plate for said casing which comprises centering the casing by means of said inner pole piece,turning down the periphery of the flange 01' the casing about the inner pole piece as a center, centering the end plate by means of the opening therein, tuming over the marginal edge of said end plate about the opening, as a center, and assembling the end plate upon the casing with the inner pole piece extending into the opening in said end plate and with the turned over margin of the end plate embracing the flange oi the casing.

PETER L. JENSEN. 

